Molecular drivers of non-alcoholic steatohepatitis are sustained in mild-to-late fibrosis progression in a guinea pig model.

Hepatic fibrosis increases mortality in humans with non-alcoholic steatohepatitis (NASH), but it remains unclear how fibrosis stage and progression affect the pathogenic mechanisms of NASH. This study investigates the transcriptional regulation and the impact of fibrosis stage, of pathways relating to hepatic lipid and cholesterol homeostasis, inflammation and fibrosis using RT-qPCR in the guinea pig NASH model. Animals were fed a chow (4% fat), a high-fat (20% fat, 0.35% cholesterol) or high-fat/high-sucrose (20% fat, 15% sucrose, 0.35% cholesterol) diet for 16 or 25 weeks (n = 7/group/time point). High-fat diets induced NASH. In NASH, markers of hepatic de novo lipogenesis were enhanced (e.g. FASN, > twofold, p < 0.05) while markers of mitochondrial, peroxisomal and cytochrome fatty acid oxidation were reduced (e.g. CPT1A > twofold, p < 0.05). Markers of fatty acid uptake were unaltered or decreased. Likewise, expression of cholesterol uptake and synthesis markers were decreased, whereas genes relating to lipid and cholesterol export were unaltered. Inflammatory and chemotactic cytokines were enhanced alongside fibrogenic pathways including increased hepatic stellate cell activation and migration, matrix deposition (e.g. MCP1, TNFα, ß-PDGF and Col1a1, > threefold, p < 0.05) and decreased matrix degradation. Fibrosis stage (mild vs. severe) and progression did generally not affect the expression of the investigated pathways. This suggests that liver dysfunction at the transcriptional level is induced early and maintained throughout fibrosis progression, allowing potential treatments to target dysregulated pathways already at early disease stages. As the guinea pig NASH model mimics several aspects of human molecular pathophysiology, these results may be used to increase the current understanding of NASH pathology and explore future treatment targets.

Molecular mechanisms of hepatic lipid accumulation in non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is currently the world's most common liver disease, estimated to affect up to one-fourth of the population. Hallmarked by hepatic steatosis, NAFLD is associated with a multitude of detrimental effects and increased mortality. This narrative review investigates the molecular mechanisms of hepatic steatosis in NAFLD, focusing on the four major pathways contributing to lipid homeostasis in the liver. Hepatic steatosis is a consequence of lipid acquisition exceeding lipid disposal, i.e., the uptake of fatty acids and de novo lipogenesis surpassing fatty acid oxidation and export. In NAFLD, hepatic uptake and de novo lipogenesis are increased, while a compensatory enhancement of fatty acid oxidation is insufficient in normalizing lipid levels and may even promote cellular damage and disease progression by inducing oxidative stress, especially with compromised mitochondrial function and increased oxidation in peroxisomes and cytochromes. While lipid export initially increases, it plateaus and may even decrease with disease progression, sustaining the accumulation of lipids. Fueled by lipo-apoptosis, hepatic steatosis leads to systemic metabolic disarray that adversely affects multiple organs, placing abnormal lipid metabolism associated with NAFLD in close relation to many of the current life-style-related diseases.

Distribution of vitamin C is tissue specific with early saturation of the brain and adrenal glands following differential oral dose regimens in guinea pigs.

Vitamin C (VitC) deficiency is surprisingly common in humans even in developed parts of the world. The micronutrient has several established functions in the brain; however, the consequences of its deficiency are not well characterised. To elucidate the effects of VitC deficiency on the brain, increased knowledge about the distribution of VitC to the brain and within different brain regions after varying dietary concentrations is needed. In the present study, guinea pigs (like humans lacking the ability to synthesise VitC) were randomly divided into six groups (n 10) that received different concentrations of VitC ranging from 100 to 1500 mg/kg feed for 8 weeks, after which VitC concentrations in biological fluids and tissues were measured using HPLC. The distribution of VitC was found to be dynamic and dependent on dietary availability. Brain saturation was region specific, occurred at low dietary doses, and the dose-concentration relationship could be approximated with a three-parameter Hill equation. The correlation between plasma and brain concentrations of VitC was moderate compared with other organs, and during non-scorbutic VitC deficiency, the brain was able to maintain concentrations from about one-quarter to half of sufficient levels depending on the region, whereas concentrations in other tissues decreased to one-sixth or less. The adrenal glands have similar characteristics to the brain. The observed distribution kinetics with a low dietary dose needed for saturation and exceptional retention ability suggest that the brain and adrenal glands are high priority tissues with regard to the distribution of VitC.

Maternal vitamin C deficiency during pregnancy results in transient fetal and placental growth retardation in guinea pigs.

PURPOSE: Recently, we reported that preferential maternal-fetal vitamin C (vitC) transport across the placenta is likely to be impaired by prolonged maternal vitC deficiency. Maintenance of a basal maternal vitC supply at the expense of the fetus may impair fetal development; however, the knowledge of vitC's impact on intrauterine development is sparse. The aim of this study was to explore the effect of maternal vitC status on fetal and placental development in guinea pigs. METHODS: Twenty pregnant Dunkin Hartley guinea pigs were randomized into four groups to receive diets either sufficient (918 mg/kg CTRL) or deficient (100 mg/kg DEF) in vitC. Cesarean sections at gestational day (GD) 45 or 56 allowed for fetal and placental measurements. RESULTS: At GD45, body, brain and placental weights were significantly reduced in DEF pups compared with CTRL (p < 0.05, p < 0.001 and p < 0.05, respectively). DEF plasma vitC levels were ~6% of those of CTRL (p < 0.0001), and the fetal/maternal plasma vitC ratio was significantly reduced at GD56 in the DEF animals compared with controls (p = 0.035). Placental vitC levels were reduced in DEF animals (p < 0.0001) and the ascorbate oxidation ratio and glutathione elevated compared with controls (p < 0.0001). CONCLUSIONS: Although no clinical differences between CTRL and DEF pups were observed at GD56, the present data suggest that vitC plays a role in early fetal development. Although no clinical differences between CTRL and DEF pups were observed at GD56, the present data suggest that vitC plays a role in early fetal development. Low maternal vitC intake during pregnancy may compromise maternal weight gain, placental function and intrauterine development.

CRISPR-Cas9 immune-evasive hESCs are rejected following transplantation into immunocompetent mice.

Although current stem cell therapies exhibit promising potential, the extended process of employing autologous cells and the necessity for donor-host matching to avert the rejection of transplanted cells significantly limit the widespread applicability of these treatments. It would be highly advantageous to generate a pluripotent universal donor stem cell line that is immune-evasive and, therefore, not restricted by the individual's immune system, enabling unlimited application within cell replacement therapies. Before such immune-evasive stem cells can be moved forward to clinical trials, in vivo testing via transplantation experiments in immune-competent animals would be a favorable approach preceding preclinical testing. By using human stem cells in immune competent animals, results will be more translatable to a clinical setting, as no parts of the immune system have been altered, although in a xenogeneic setting. In this way, immune evasiveness, cell survival, and unwanted proliferative effects can be assessed before clinical trials in humans. The current study presents the generation and characterization of three human embryonic stem cell lines (hESCs) for xenogeneic transplantation in immune-competent mice. The major histocompatibility complexes I- and II-encoding genes, B2M and CIITA, have been deleted from the hESCs using CRISPR-Cas9-targeted gene replacement strategies and knockout. B2M was knocked out by the insertion of murine CD47. Human-secreted embryonic alkaline phosphatase (hSEAP) was inserted in a safe harbor site to track cells in vivo. The edited hESCs maintained their pluripotency, karyotypic normality, and stable expression of murine CD47 and hSEAP in vitro. In vivo transplantation of hESCs into immune-competent BALB/c mice was successfully monitored by measuring hSEAP in blood samples. Nevertheless, transplantation of immune-evasive hESCs resulted in complete rejection within 11 days, with clear immune infiltration of T-cells on day 8. Our results reveal that knockout of B2M and CIITA together with species-specific expression of CD47 are insufficient to prevent rejection in an immune-competent and xenogeneic context.

Novel traceable CRISPR-Cas9 engineered human embryonic stem cell line (E1C3 + hSEAP + 2xKO + pCD47), has potential to evade immune detection in pigs.

Here we present the generation of a human embryonic stem cell line with the potential to escape immune rejection upon transplantation to an alternate species, in this case sus scrofa. For in vivo detection the cells were modified by CRISPR-Cas9 to express human secreted alkaline phosphatase. To avoid immune recognition and subsequent rejection by host, genes encoding hB2M and hCIITA were knocked out and the porcine gene for CD47 was introduced. Upon editing and subsequent culture, cells maintained molecular and phenotypic pluripotent charactaristics and a normal karyotype supporting viability and functionality of the engineered cell line.

Prolonged maternal vitamin C deficiency overrides preferential fetal ascorbate transport but does not influence perinatal survival in guinea pigs.

Human and guinea pig fetuses are completely dependent on an adequate maternal vitamin C (vitC) intake. Shortage of micronutrients can have negative implications for fetal health and pregnancy outcome; however, knowledge of maternal vitC deficiency's impact on fetal development is sparse and reports of pregnancy outcome have been divergent. The present study investigated whether maternal vitC deficiency affects pregnancy outcome and plasma vitC distribution between the mother and the offspring in a guinea pig model. A total of eighty pregnant Dunkin Hartley guinea pigs were randomised into two weight-stratified groups receiving either a deficient (100 mg/kg DEF) or a control (923 mg/kg CTRL) diet. VitC levels were measured in plasma during pregnancy and postpartum, and in the plasma and brain of newborns. Pregnancy outcome was recorded with respect to birth weight and perinatal survival and were similar between groups. Plasma vitC in dams declined throughout gestation in both groups (P< 0·01). Compared with maternal plasma vitC, plasma vitC of newborn pups was found to be significantly lower in the DEF group (P< 0·001) and higher in the CTRL group (P< 0·001), respectively. Brain vitC levels were significantly reduced in DEF newborn pups (P< 0·001). The present results indicate that preferential transport of vitC from the mother to the fetus is overridden during sustained maternal vitC deficiency, maintaining maternal vitC concentration at the expense of the offspring. This contradicts the notion that a fetus is protected from vitC deficiency by the placental Na-dependent vitC co-transporter, SVCT2, thus fetal development may be susceptible to the negative effects of maternal vitC deficiency.

Validation of computed tomography as a diagnostic tool in guinea pigs with non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) and subsequent steatohepatitis (NASH) is the most common cause of liver disease and liver transplantation in humans. Affecting millions of patients worldwide, diagnosis relies on a biopsy, not without risk to the patient, and emphasises the need for improved diagnostic measures to determine and monitor disease progression. Despite intensive research, approved pharmacological treatment modalities are few, underlining that animal models with increased translational validity are important to advance preclinical drug development. This study validates the applicability of computed tomography (CT) as a non-invasive diagnostic tool for the assessment of liver steatosis in a guinea pig model of NAFLD/NASH. Guinea pigs with induced NAFLD or NASH were compared to healthy controls at two separate time points: week 16, serving as baseline measure, and week 25 to monitor disease progression over time. The animals were subsequently euthanised, and samples were collected to confirm disease stage. The data showed a strong negative correlation between liver triglycerides and Hounsfield unit (HU) values (R2 = 0.8157; p < 0.0001). A significant difference in histopathological scoring and HU values between grade 0 and more advanced stages of steatosis was recorded (p < 0.001), although the degree of liver fibrosis could not be accurately evaluated by differences in HU. In conclusion, the present study validates CT scanning for the determination of hepatic steatosis in guinea pigs, and it strongly supports the technique as a relevant non-invasive diagnostic tool in this species.

Dietary Long-Chain Fatty Acids Accelerate Metabolic Dysfunction in Guinea Pigs with Non-Alcoholic Steatohepatitis.

The composition of dietary fatty acids may be important for the development and progression of metabolic syndrome and non-alcoholic steatohepatitis (NASH). This study investigated the effect of two high-fat diets based on coconut oil, containing predominantly medium-chain fatty acids (MCFA), or cocoa butter, containing mainly long-chain fatty acids (LCFA), on glucose homeostasis and NASH in guinea pigs following 16 and 32 weeks of diet. At week 16, glucose intolerance was increased in the LCFA animals compared to the MCFA animals (p < 0.001), with both groups differing from the controls by week 32 (p < 0.0001), supported by increased hemoglobin A1c (p < 0.05). NASH was present in both high-fat groups from week 16, with advancing fibrosis appearing more progressive in the LCFA animals at week 16. In agreement, gene expression showed overall increased expression of NASH target genes in the LCFA animals compared to the MCFA animals at weeks 16 and 32 (p < 0.05 and p < 0.0001, respectively). The LCFA animals also displayed increased plasma uric acid at both time points (p < 0.05), a phenomenon linked to NASH in humans. In conclusion, this study reports that a diet high in LCFA promotes metabolic imbalance and may accelerate NASH-associated hepatic fibrosis. This highlights the importance of a critical evaluation of fatty acid composition when investigating NASH-associated endpoints.

Efficacy of fibroblast growth factor 21 in non-alcoholic fatty liver disease in guinea pigs.

Fibroblast growth factor 21 (FGF21) agonists have shown promising effects in preclinical models of non-alcoholic fatty liver disease (NAFLD) as well as in short-term clinical trials in patients with non-alcoholic steatohepatitis (NASH). Comparing drug formulation, dose, administration route and age, this exploratory study investigated effects of FGF21 on NAFLD-associated measures in a validated guinea pig model. In three separate studies, female guinea pigs received a high-fat diet prior to intervention with escalating doses of either recombinant native human FGF21 or a human FGF21 human recombinant analogue (FGF21/19 chimer) with an extended half-life. While no significant effects of native FGF21 on the investigated endpoints were observed, the long-acting FGF21/19 chimer significantly altered the levels of circulating lipids, increasing plasma concentrations of cholesterol (TC, LDLc and HDLc) in young guinea pigs (p < 0.01 for all three parameters). Relative liver weights were reduced in FGF21/19-treated young animals (p < 0.05) compared to mature animals, whereas FGF21/19 reduced body weights in both age groups (p < 0.001). The FGF21/19 chimer effects on dyslipidemia, body and liver weights particularly in young animals, support an age-associated difference in the FGF21 response. The limited effects of the native human FGF21 highlights potential species-associated differences of this compound.

Vitamin C Deficiency Exacerbates Dysfunction of Atherosclerotic Coronary Arteries in Guinea Pigs Fed a High-Fat Diet.

Vitamin C (vitC) deficiency has been associated with an increased risk of cardiovascular disease; while several putative mechanistic links have been proposed, functional evidence supporting a causal relationship is scarce. In this study, we investigated how vitC deficiency affects coronary artery vasomotor function and the development of coronary atherosclerotic plaques in guinea pigs subjected to chronic dyslipidemia by a high-fat diet regime. Female Hartley guinea pigs were fed either a control (low-fat diet and sufficient vitC) (N = 8) or a high-fat diet with either sufficient (N = 8) or deficient (N = 10) vitC for 32 weeks. Guinea pigs subjected to the high-fat diet developed significant atherosclerotic plaques in their coronary arteries, with no quantitative effect of vitC deficiency. In isolated coronary arteries, vasomotor responses to potassium, carbachol, nitric oxide, or bradykinin were studied in a wire myograph. Carbachol, bradykinin, and nitric oxide mediated relaxation in the coronary arteries of the control group. While vasorelaxation to carbachol and nitric oxide was preserved in the two high-fat diet groups, bradykinin-induced vasorelaxation was abolished. Interestingly, bradykinin induced a significant contraction in coronary arteries from vitC-deficient guinea pigs (p < 0.05). The bradykinin-induced contraction was unaffected by L-NAME but significantly inhibited by both indomethacin and vitC, suggesting that, during vitC deficiency, increased release of arachidonic acid metabolites and vascular oxidative stress are involved in the constrictor effects mediated by bradykinin. In conclusion, the present study shows supporting evidence that poor vitC status negatively affects coronary artery function.

High dietary fat and cholesterol exacerbates chronic vitamin C deficiency in guinea pigs.

Vitamin C deficiency - or hypovitaminosis C defined as a plasma concentration below 23 µm - is estimated to affect hundreds of millions of people in the Western world, in particular subpopulations of low socio-economic status that tend to eat diets of poor nutritional value. Recent studies by us have shown that vitamin C deficiency may result in impaired brain development. Thus, the aim of the present study was to investigate if a poor diet high in fat and cholesterol affects the vitamin C status of guinea pigs kept on either sufficient or deficient levels of dietary ascorbate (Asc) for up to 6 months with particular emphasis on the brain. The present results show that a high-fat and cholesterol diet significantly decreased the vitamin C concentrations in the brain, irrespective of the vitamin C status of the animal (P < 0·001). The brain Asc oxidation ratio only depended on vitamin C status (P < 0·0001) and not on the dietary lipid content. In plasma, the levels of Asc significantly decreased when vitamin C in the diet was low or when the fat/cholesterol content was high (P < 0·0001 for both). The Asc oxidation ratio increased both with low vitamin C and with high fat and cholesterol content (P < 0·0001 for both). We show here for the first time that vitamin C homoeostasis of brain is affected by a diet rich in fat and cholesterol. The present findings suggest that this type of diet increases the turnover of Asc; hence, individuals consuming high-lipid diets may be at increased risk of vitamin C deficiency.

Vitamin C Deficiency in the Young Brain-Findings from Experimental Animal Models.

Severe and long-term vitamin C deficiency can lead to fatal scurvy, which is fortunately considered rare today. However, a moderate state of vitamin C (vitC) deficiency (hypovitaminosis C)-defined as a plasma concentration below 23 µM-is estimated to affect up to 10% of the population in the Western world, albeit clinical hallmarks in addition to scurvy have not been linked to vitC deficiency. The brain maintains a high vitC content and uniquely high levels during deficiency, supporting vitC's importance in the brain. Actions include both antioxidant and co-factor functions, rendering vitamin C deficiency likely to affect several targets in the brain, and it could be particularly significant during development where a high cellular metabolism and an immature antioxidant system might increase sensitivity. However, investigations of a non-scorbutic state of vitC deficiency and effects on the developing young brain are scarce. This narrative review provides a comprehensive overview of the complex mechanisms that regulate vitC homeostasis in vivo and in the brain in particular. Functions of vitC in the brain and the potential consequences of deficiency during brain development are highlighted, based primarily on findings from experimental animal models. Perspectives for future investigations of vitC are outlined.

Extracellular Vesicles as Drivers of Non-Alcoholic Fatty Liver Disease: Small Particles with Big Impact.

Nonalcoholic fatty liver disease (NAFLD) is becoming the leading chronic liver disease, negatively affecting the lives of millions of patients worldwide. The complex pathogenesis involves crosstalk between multiple cellular networks, but how the intricate communication between these cells drives disease progression remains to be further elucidated. Furthermore, the disease is not limited to the liver and includes the reprogramming of distant cell populations in different organs. Extracellular vesicles (EVs) have gained increased attention as mediators of cellular communication. EVs carry specific cargos that can act as disease-specific signals both locally and systemically. Focusing on NAFLD advancing to steatohepatitis (NASH), this review provides an update on current experimental and clinical findings of the potential role of EVs in hepatic inflammation and fibrosis, the main contributors to progressive NASH. Particular attention is placed on the characteristics of EV cargos and potential specificity to disease stages, with putative value as disease markers and treatment targets for future investigations.

Hepatic Stellate Cell Activation and Inactivation in NASH-Fibrosis-Roles as Putative Treatment Targets?

Hepatic fibrosis is the primary predictor of mortality in patients with non-alcoholic steatohepatitis (NASH). In this process, the activated hepatic stellate cells (HSCs) constitute the principal cells responsible for the deposition of a fibrous extracellular matrix, thereby driving the hepatic scarring. HSC activation, migration, and proliferation are controlled by a complex signaling network involving growth factors, lipotoxicity, inflammation, and cellular stress. Conversely, the clearance of activated HSCs is a prerequisite for the resolution of the extracellular fibrosis. Hence, pathways regulating the fate of the HSCs may represent attractive therapeutic targets for the treatment and prevention of NASH-associated hepatic fibrosis. However, the development of anti-fibrotic drugs for NASH patients has not yet resulted in clinically approved therapeutics, underscoring the complex biology and challenges involved when targeting the intricate cellular signaling mechanisms. This narrative review investigated the mechanisms of activation and inactivation of HSCs with a focus on NASH-associated hepatic fibrosis. Presenting an updated overview, this review highlights key cellular pathways with potential value for the development of future treatment modalities.

The development of nonalcoholic steatohepatitis is subjected to breeder dependent variation in guinea pigs.

Variability in disease development due to differences in strains and breeders constitutes a substantial challenge in preclinical research. However, the impact of the breeder on non-alcoholic steatohepatitis (NASH) is not yet fully elucidated. This retrospective study investigates NASH development in guinea pigs from Charles River or Envigo fed a high fat diet (20% fat, 15% sucrose, 0.35% cholesterol) for 16 or 24/25 weeks. Charles River animals displayed more severe NASH, with higher steatosis (p < 0.05 at week 16), inflammation (p < 0.05 at both week), fibrosis (p < 0.05 at week 16) and disease activity (p < 0.05 at both weeks). Accordingly, alanine and aspartate aminotransferase were increased at week 24/25 (p < 0.01). Hepatic expression of inflammatory (Ccl2, Cxcl8) and fibrotic (Pdgf, Serpine1, Col1a1) genes was also increased (p < 0.05). Differences were observed in healthy chow (4% fat, 0% sucrose, 0% cholesterol) fed animals: Envigo animals displayed higher relative liver weights (p < 0.01 at both weeks), liver cholesterol (p < 0.0001 at week 24/25) and aspartate aminotransferase (p < 0.05 at week 16), but lower levels of alkaline phosphatase (p < 0.0001 at week 24/25). These findings accentuates the importance of the breeder and its effect on NASH development and severity. Consequently, this may affect reproducibility, study comparison and limit the potential of developing novel therapies.

Decreased expression of the GLP-1 receptor after segmental artery injury in mice.

The glucagon-like peptide-1 receptor (GLP1R) is expressed in the renal vasculature and known to be downregulated under hypertensive conditions in rats and humans. However, little is known about the regulation in other types of renal pathology involving vascular changes. This study investigates the expression of the GLP1R in renal vasculature after glomerular injury in the nephrotoxic nephritis mouse model, high cholesterol, and atherosclerosis in the Ldlr-/- mouse on Western diet, and ex vivo injury in an organ culture model. The immunohistochemical signal of the GLP1R was significantly decreased in arteries from mice with nephrotoxic nephritis after 42 days compared to 7 days and saline control (P < 0.05). Histological evaluation of kidneys from Ldlr-/- mice on Western diet showed a decreased GLP1R specific immunohistochemical signal (P < 0.05). The dilatory response to liraglutide was decreased in Western diet fed Ldlr-/- mice compared to C57Bl/6J controls (P < 0.05). Organ culture significantly decreased the immunohistochemical signal of the GLP1R (P <0.05) and the expression of Glp1r mRNA (P < 0.005) compared to fresh. Organ cultured vessels showed vascular smooth muscle cell remodelling as Acta2 expression was decreased (P < 0.005) and Ednrb was increased (P < 0.05). In conclusion, nephrotoxic nephritis and hypercholesterolaemia led to decreased GLP1R specific immunohistochemical signal. Ex vivo vascular injury in the organ culture model leads to a decrease in expression of GLP1R expressionand contractile VSMC specific markers and increase in expression of dedifferentiation markers suggestive of an inverse relationship between phenotypic switch of the VSMC and the expression of the GLP1R; however, the causal relationship remains elusive.

Liraglutide treatment improves endothelial function in the Ldlr-/- mouse model of atherosclerosis and affects genes involved in vascular remodelling and inflammation.

Recent clinical intervention studies have shown that the GLP1 analogue liraglutide lowers cardiovascular risk, but the underlying mechanism has not yet been fully elucidated. This study investigated the effects of liraglutide on endothelial function in the Ldlr-/- mouse model. Mice (n = 12/group) were fed Western diet (WD) or chow for 12 weeks followed by 4 weeks of treatment with liraglutide (1 mg/kg/day) or vehicle subcutaneously. Weight loss, blood lipid content, plaque burden, vasomotor function of the aorta and gene expression pattern in aorta and brachiocephalic artery were monitored. Liraglutide treatment significantly induced weight loss (P < .0001), decreased blood triglycerides (P < .0001) and total cholesterol (P < .0001) in WD-fed mice but did not decrease plaque burden. Liraglutide also improved endothelium-mediated dilation of the distal thoracis aorta (P = .0067), but it did not affect phenylephrine or sodium nitroprusside responses. Fluidigm analyses of 96 genes showed significantly altered expression of seven genes related to inflammation, vascular smooth muscle cells and extracellular matrix composition in liraglutide-treated animals. We conclude that treatment with liraglutide decreased endothelial dysfunction and that this could be linked to decreased inflammation or regulation of vascular remodelling.

Modelling Nonalcoholic Steatohepatitis In Vivo-A Close Transcriptomic Similarity Supports the Guinea Pig Disease Model.

The successful development of effective treatments against nonalcoholic steatohepatitis (NASH) is significantly set back by the limited availability of predictive preclinical models, thereby delaying and reducing patient recovery. Uniquely, the guinea pig NASH model develops hepatic histopathology and fibrosis resembling that of human patients, supported by similarities in selected cellular pathways. The high-throughput sequencing of guinea pig livers with fibrotic NASH (n = 6) and matched controls (n = 6) showed a clear separation of the transcriptomic profile between NASH and control animals. A comparison to NASH patients with mild disease (GSE126848) revealed a 45.2% overlap in differentially expressed genes, while pathway analysis showed a 34% match between the top 50 enriched pathways in patients with advanced NASH (GSE49541) and guinea pigs. Gene set enrichment analysis highlighted the similarity to human patients (GSE49541), also when compared to three murine models (GSE52748, GSE38141, GSE67680), and leading edge genes THRSP, CCL20 and CD44 were highly expressed in both guinea pigs and NASH patients. Nine candidate genes were identified as highly correlated with hepatic fibrosis (correlation coefficient > 0.8), and showed a similar expression pattern in NASH patients. Of these, two candidate genes (VWF and SERPINB9) encode secreted factors, warranting further investigations as potential biomarkers of human NASH progression. This study demonstrates key similarities in guinea pig and human NASH, supporting increased predictability when translating research findings to human patients.

A Long-Term Energy-Rich Diet Increases Prefrontal BDNF in Sprague-Dawley Rats.

Findings of the effect of high-fat feeding including "Cafeteria Diets" (CAF) on brain-derived neurotrophic factor (BDNF) in the hippocampus (HIP) and prefrontal cortex (PFC) in rodents are conflicting. CAF is a non-standardized, highly palatable energy-rich diet composed by everyday food items for human consumption and is known to induce metabolic syndrome and obesity in rats. However, the highly palatable nature of CAF may counteract a negative effect of chronic stress on anticipatory behavior and synaptic plasticity in the hippocampus, hence represent a confounding factor (e.g., when evaluating functional effects on the brain). This study investigated the effects of a chronic, restricted access to CAF on BDNF, monoamine neurotransmitters, and redox imbalance in HIP and PFC in male rats. Our results show that CAF induced BDNF and its receptor TrkB in PFC compared to the controls (p < 0.0005). No differences in monoamine neurotransmitters were detected in either PFC or HIP. CAF increased dehydroascorbic acid and decreased malondialdehyde in PFC (p < 0.05), suggesting an early redox imbalance insufficient to induce lipid peroxidation. This study supports that a chronic CAF on a restricted schedule increases BDNF levels in the PFC of rats, highlighting that this may be a suboptimal feeding regime when investigating the effects of diet-induced obesity in the brain and emphasizing this as a point of attention when comparing the findings.